Promising Au&CNTs@N-Doped Hierarchical Carbon Composite for High-Performance Lithium–Sulfur Batteries

Abstract

A lithium–sulfur battery with an ultrahigh specific capacity of 1675 mAh g–1 is witnessed to be one of the most promising high-energy-density storage devices. However, the commercialization is restricted by the poor conductivity of sulfur, the "shuttle effect" of polysulfides, and the volume expansion during the charge/discharge process. Herein, Au&CNTs@N-doped hierarchical porous carbon material was prepared in view of structural design, chemical modification, and metal catalysis. Sulfur can be effectively accommodated and protected in the hierarchical porous carbon host; besides, the overall conductivity and structural stability of the carbon/sulfur composite are able to be enhanced by carbon nanotubes interconnected between hollow carbon spheres. Furthermore, the redox reaction kinetics of lithium polysulfides and the chemical adsorption to polysulfide are enhanced by Au atoms and doped N heteroatoms. As a result of the multifunctional features, Au&CNTs@ND-C/S exhibits an initial discharge capacity of 1256 mAh g–1 at the current density of 0.8 A g–1, with 1031 mAh g–1 remaining after 50 cycles. Overall, the multifunctional Au&CNTs@N-doped hierarchical carbon materials can effectively facilitate the electrochemical performance of the sulfur cathode through physical confinement, chemical adsorption, and catalytic enhancement.